When beautiful postgraduate Myrna Parkin came to work at his Observatory, the unhappy life of divorced Chief Astronomer Mal Spragg was turned around. But Spragg's happiness was not to last after he received a mysterious letter from an aged amateur astronomer in the Scottish highlands, the Reverend Gulvain. The letter had only been posted following Gulvain's death.

Spragg learned how the man had built his own telescope and devoted the last years of his life fighting cold, stiffness, and weakening eyes, fired by his dedication and conviction to find the fulfilment of a terrifying biblical prophecy. And then Spragg verified his discovery-a previously unknown planetoid had entered the solar system, and was on a collision path with Earth!